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題目・講義名
Loschmidt echo and dynamical fidelity in periodically driven quantum system
講師・担当教員
Ms. Shraddha Sharma (Indian Institute of Technology Kanpur, India)
日時
2014年5月16日(金)10:45-12:15
場所
大岡山 本館2階 H284B 物理学科輪講室
要旨
We study the dynamical fidelity and the Loschmidt echo, following a periodic driving of the transverse magnetic field of a quantum Ising chain (across the quantum critical point) which is calculated through the overlap between the initial ground state and the state reached after n periods (calculated using the Floquet theory). We show that the logarithm of the fidelity per-site reaches a steady value in the asymptotic limit of n, and we derive an exact analytical expression for this quantity. Remarkably, unlike thermodynamic quantities such as energy and transverse magnetization, the steady state value of logarithm of the fidelity per-site cannot be derived by using a decohered density matrix, and keeps memory of non-trivial phase information.

連絡先
物性物理学専攻 西森 秀稔(内線2488)
講義資料(PDF)
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